The present invention relates to methods and apparatus for administering therapeutic gaseous substances into the nostril of a patient.
In the medical treatment of patients it is often necessary to delivery oxygen or other therapeutic gaseous substances to the patient's respiratory system. This has been heretofore achieved by means of nasal cannulas such as the type disclosed in U.S. Pat. No. 2,868,199 issued to Hudson on Jan. 13, 1959, and U.S. Pat. No. 3,726,275 issued to Jackson et al on Apr. 10, 1973.
In the medical treatment of patients it is also sometimes necessary to perform a surgical operation called tracheostomy or to perform endotracheal intubation, both of which involve significant risks. Among the purpose of these procedures is to eliminate a portion of dead space rebreathing of exhaled air containing carbon dioxide. There is presently no known way for reducing dead space ventilation other than endotracheal intubation or perform a tracheostomy.
Some nasal cannulas heretofore employed have comprised a flexible duct which is to be connected to a source of pressurized gas to be administered. A pair of short tubes communicate with the duct and are loosely received within the nasal cavities of the patient. When installed, the tubes are able to conduct gas from the duct to the nasal cavities, whereupon the gases are inhaled and exhaled by the patient.
The inhaled gases, which may comprise a mixture of room air and therapeutic gas, travel through each nasal cavity, and into the pharynx. The inhaled gases fill all voids and recesses within the nasal cavities before reaching the pharynx. Such voids may be considered "dead space" because the gases therein at the end of inhalation never reach the gas exchange areas of the lung, and are discharged during subsequent exhalation. It will be appreciated, then, that much of the inhaled gas will merely occupy the dead air spaces, rather than reach the gas exchange areas of the lung (i.e., the alveoli) to be of therapeutic benefit to the patient.
It can be understood that during exhalation, normally exhaled air with an increased carbon dioxide level (carbon dioxide produced in the body is a waste product of respiration) is exiting through the nasal and/or oral passages thus filling these cavities at the very end of exhalation. This spent respiratory air must necessarily be re-inhaled before and ahead of any therapeutic gas and/or ambient air.
Of course, the effects of dead air space can be reduced by tracheotomy or intubation which bypasses some of the dead space but such procedures involve significant risk and discomfort not present when using a cannula-type instrument, such as is an object of this invention. Conventional oxygen therapy cannulas do nothing to reduce the effects of dead space rebreathing. Breathing masks have also been employed, however, such masks actually increase effective dead air space, are relatively uncomfortable to the patient, and must be removed when eating, expectorating, etc., all of which demonstrates the need for new and improved methods and apparatus for administering therapeutic gases.
Thus, the only known effective ways of reducing the amount of dead space carbon dioxide the patient needs to re-inhale comprise hazardous tracheostomy or endotracheal intubation operations.
Another problem involved with the delivery of therapeutic gas via conventional nasal oxygen cannulas occur when the patient "mouthbreaths", i.e., has his mouth open during breathing. In such instances a substantial portion of the breathing action will be applied through the mouth rather than through the nose, thereby minimizing the amount of inhalation occurring through the nose. Accordingly, the therapeutic benefit of the gas thus administered will as least be greatly reduced. In such instances, reliance is placed on the chance that small amounts of unspent therapeutic gases will be exhaled from the nose to a location ahead of the mouth to be subsequently inhaled through the mouth.
Because a patient may readily change from nose breathing to mouth breathing and back again, the amount and concentration of therapeutic gas reaching his lungs varies greatly.
It is therefore, an object of the invention to minimize or obviate problems of the above-discussed type.
It is a further object of the invention to maximize the therapeutic benefit to a patient of nasal-supplied gases.
It is an additional object of the invention to provide methods and apparatus for administering the therapeutic gas through a patient's nose in a manner minimizing the effects of rebreathing of carbon dioxide laden dead space air within the nasal and/or oral cavities.
It is another object of the invention to minimize the amount of dead space carbon dioxide inhaled by a patient without the need for tracheostomy or endotracheal intubation.
It is an additional object of this invention to provide new, and more efficient and comfortable means of administering therapeutic gases in high concentration than with presently employed oxygen therapy masks.